Liquid crystalline filter dyes for imaging elements

ABSTRACT

A dispersion comprises a solvent having dispersed therein a liquid-crystal forming dye of structural Formula I, II or III:                    
     wherein the substituent are as defined in the specification. 
     The dispersion is particularly useful in imaging and photographic elements.

This is a Divisional of application Ser. No. 09/151,976, filed Sep. 11,1998, now U.S. Pat. No. 6,093,510.

FIELD OF THE INVENTION

This invention relates to a dispersion of a dye in a solvent wherein thedye forms a lyotropic liquid crystalline phase, a method for preparingsaid dispersions, an imaging element containing said dispersion and aphotographic element containing said dispersion.

BACKGROUND OF THE INVENTION

Radiation-sensitive materials, including light-sensitive materials, suchas photographic materials, may utilize filter dyes for a variety ofpurposes. Filter dyes may be used to adjust the speed of aradiation-sensitive layer; they may be used as absorber dyes to increaseimage sharpness of a radiation-sensitive layer; they may be used asantihalation dyes to reduce halation; they may be used to reduce theamount or intensity of radiation from reaching one or moreradiation-sensitive layers, and they may also be used to preventradiation of a specific wavelength or range of wavelengths from reachingone or more of the radiation-sensitive layers in a radiation-sensitiveelement. For each of these uses, the filter dye(s) may be located in anynumber of layers of a radiation-sensitive element, depending on thespecific requirements of the element and the dye, and on the manner inwhich the element is to be exposed. The amount of filter dyes usedvaries widely, but they are preferably present in amounts sufficient toalter in some way the response of the element to radiation. Filter dyesmay be located in a layer above a radiation-sensitive layer, in aradiation-sensitive layer, in a layer below a radiation-sensitive layer,or in a layer on the opposite side of the support from aradiation-sensitive layer.

Photographic materials often contain layers sensitized to differentregions of the spectrum, such as red, blue, green, ultraviolet,infrared, X-ray, to name a few. A typical color photographic elementcontains a layer sensitized to each of the three primary regions of thevisible spectrum, i.e., blue, green, and red. Silver halide used inthese materials has an intrinsic sensitivity to blue light. Increasedsensitivity to blue light, along with sensitivity to green light or redlight, is imparted through the use of various sensitizing dyes adsorbedto the silver halide grains. Sensitized silver halide retains itsintrinsic sensitivity to blue light.

There are numerous applications for which filtration or absorbance ofvery specific regions of light are highly desirable. Some of theseapplications, such as yellow filter dyes and magenta trimmer dyes,require non-diffusing dyes which may be coated in a layer-specificmanner to prevent specific wavelengths of light from reaching specificlayers of the film during exposure. These dyes must have sharp-cuttingedges on the bathochromic (long-wavelength) side of the absorbanceenvelope to prevent light punch through without adversely affecting thespeed of the underlying emulsions. In other applications, it isdesirable to allow passage of light below a certain wavelength. In thesecases it is desirable to have a dye which is very sharp-cutting on thehypsochromic (short-wavelength) edge of the absorbance envelope.Depending on the location of these filter layers relative to thesensitized silver halide emulsion layers, it would also be desirable tohave non-diffusing, layer-specific filter dyes with absorption spectrawhich are sharp-cutting on the hypsochromic edge as well as thebathochromic edge. Such dyes are sometimes known as “finger filters”.Preferably these dyes should exhibit high extinction coefficients,narrow half bandwidths and sharp cutting hypsochromic and bathochromicabsorption envelopes when incorporated into imaging elements includingphotographic elements. Typically, to achieve these properties, isotropicsolutions of dyes have been incorporated. Dyes introduced by thismethod, however, often wander into adjacent layers causing problems suchas speed loss or stain, and cannot be coated in a layer-specific mannerwithout the use of mordants. Solubilized dyes may be mordanted toprevent wandering through adjacent layers. While the use of polymericmordants can prevent dye wandering, such mordants aggravate the stainproblem encountered when the dye remains in the element throughprocessing.

Dyes with a high extinction coefficient allow maximum light absorptionusing a minimum amount of dye. Lower requisite dye laydown reduces thecost of light filtration and produces fewer processing by-products.Lower dye laydowns may also result in reduced dye stain in shortduration processes.

Finger filters such as described above are highly desirable for otheruses such as protecting silver halide sensitized emulsions from exposureby safelights. Such dyes must have absorbance spectra with highextinction coefficients and narrow halfbandwidths, and sharp cuttingabsorbance envelopes to efficiently absorb light in the narrowsafelight-emitting region without adversely affecting the speed of thesensitized silver halide emulsions. This affords protection for thesensitized emulsion from exposure by light in the safelight's spectralregion. Useful absorbance maxima for safelight dyes include, but are notrestricted to 490-510 nm and 590-610 nm.

Similar properties are required for infrared absorbing filter dyes.Laser-exposed radiation-sensitive elements require high efficiency lightabsorbance at the wavelength of laser emission. Unwanted absorbance frombroadly absorbing dyes reduces the efficiency of light capture at thelaser emission wavelength, and requires the use of larger amounts of dyeto adequately cover the desired spectral region. In photographicelements, unwanted absorbance may also cause speed losses in adjacentsilver halide sensitized layers if the photographic element has multiplesensitized layers present. Useful finger filter absorbance maxima forabsorbing laser and phosphor emissions include but are not restricted to950 nm, 880 nm, 830 nm, 790 nm, 633 nm, 670 nm, 545 nm and 488 nm.

In some radiation sensitive elements, including dry process imagingfilms, it is necessary to provide light filtration or antihalation atdeep cyan and infrared wavelengths. Typically such protection has beenachieved using water or solvent soluble dyes or milled solid particledyes. Typically, water-soluble dyes forming isotropic solutions canprovide relatively sharp, high extinction absorbance, but are prone tointerlayer wandering.

One common use for filter dyes is in silver halide light sensitivephotographic elements. If, prior to processing, blue light reaches alayer containing silver halide which has been sensitized to a region ofthe spectrum other than blue, the silver halide grains exposed to theblue light, by virtue of their intrinsic sensitivity to blue light,would be rendered developable. This would result in a false rendition ofthe image information being recorded in the photographic element. It istherefore a common practice to include in the photographic element amaterial that filters blue light. This blue-absorbing material can belocated anywhere in the element where it is desirable to filter bluelight. In a color photographic element that has layers sensitized toeach of the primary colors, it is common to have the blue-sensitizedlayer closest to the exposure source and to interpose a blue-absorbing,or yellow filter layer between the blue-sensitized layer and the green-and red-sensitized layers.

Another common use for filter dyes is to filter or trim portions of theUV, visible or infrared spectral regions to prevent unwanted wavelengthsof light from reaching sensitized emulsions. Just as yellow filter dyesprevent false color rendition from the exposure of emulsions sensitizedto a region of the spectrum other than blue, filter dyes absorbing inthe UV, magenta, cyan and infrared spectral regions can prevent falsecolor rendition by shielding sensitized emulsion layers from exposure tospecific wavelength regions. One application of his strategy is the useof green-absorbing magenta trimmer dyes. In one type of typical colorphotographic element containing a layer sensitized to each of the threeprimary regions of the visible spectrum, i.e., blue, green, and red, thegreen-sensitized layer is coated above the red-sensitized layer andbelow the blue-sensitized layer. Depending on the chosen spectralsensitivity maxima for the sensitized silver halide layers, there may bea region of overlap between the spectral sensitivities of the green andred emulsions. Under such circumstances, green light which is notabsorbed by the green-sensitive emulsion can punch through to the redsensitive emulsion and be absorbed by the leading edge of the redspectral sensitizing dye. This crosstalk between the green and redemulsions results in false color rendition. It would, therefore, behighly desirable to find a green-absorbing filter dye which uponincorporation into a photographic element would absorb strongly aroundthe spectral maximum of the green-sensitized emulsion, and possess asharp cutting bathochromic absorbance such that there is no appreciableabsorbance just bathochromic to its absorbance maximum. A sharp-cuttingbathochromic edge on a filter or trimmer dye enables excellent colorreproduction with minimum speed loss by absorbing light efficiently upto its absorbance maximum, but very little if any just past itsabsorbance maximum. For example, a yellow filter dye (blue absorber)which is only moderately sharp-cutting on the bathochromic edge mayfunction adequately as a filter dye, but its unwanted absorbance in thegreen region past its λ_(max) will rob the green-sensitive emulsioncoated below it of green light and hence speed. Though the position ofoptimal absorption maximum for a magenta trimmer dye will vary dependingon the photographic element being constructed, it is particularlydesirable in one type of typical color photographic element containing alayer sensitized to each of the three primary regions of the visiblespectrum, i.e., blue, green, and red, that a magenta trimmer dye absorbstrongly at about 550 nm, and possess a sharp cutting bathochromicabsorbance such that there is no appreciable absorbance above about 550nm. Therefore it would be desirable to provide a filter dye for use inphotographic elements that possesses high requisite absorbance in thegreen region of the spectrum below about 550 nm, but little or noabsorbance above about 550 nm, and furthermore does not suffer fromincubative or post process stain problems, and furthermore is not proneto migration in the coated film, but is fully removed upon processing.

One method used to incorporate solvent or water-soluble filter dyes intophotographic film element layers is to add them as aqueous or alcoholicisotropic solutions. Dyes introduced by this method are generally highlymobile and rapidly diffusing and often wander into other layers of theelement, usually with deleterious results. While the use of polymericmordants can prevent dye wandering, such mordants aggravate the stainproblem encountered when the dye remains in the element throughprocessing.

Filter dyes have also been prepared as conventional dispersions inaqueous gelatin using standard colloid milling or homogenization methodsor as loaded latices. More recently, ball-milling, sand-milling,media-milling and related methods of producing fine-particle-sizeslurries and suspensions of solid filter dyes have become standard toolsfor producing slurries and dispersions that can readily be used inphotographic melt formulations. Solid particle filter dyes introduced asdispersions, when coated at sufficiently low pH, can eliminate problemsassociated with dye wandering. However, solvent-insoluble solid particlefilter dyes (pigments) provide relatively low absorption coefficients,requiring that an excessive amount of dye be coated. In addition, it isvery difficult to find classes of solid particle dispersion dyes whichconsistently yield useful, sharp-cutting bathochromic or hysochromicspectral features due to their microcrystalline nature. In fact the hueof a microcrystalline dye is highly unpredictable and often variestremendously between similar analogs. In addition many solid particledyes are not robust under keeping conditions of high heat and humidityexperienced in melting and coating operations. Under such conditions,microcrystals of dye can undergo ripening, resulting in a lower opticaldensity post incubation. In addition, the time and expense involved inpreparing serviceable solid particle filter dye dispersions by millingtechniques are a deterrent to their use, especially in large volumeapplications. It is therefore desirable to provide dye dispersions thatdo not necessarily require mechanical milling before use and that do notwander but that wash out easily during processing leaving little or noresidual stain. It is also desirable that such filter dye dispersionsprovide high light absorption efficiencies with sharp-cutting absorbancepeaks. One method of obtaining these desirable dye features in solidparticle dispersions of oxonol filter dyes was described by Texter (U.S.Pat. No. 5,274,109, U.S. Pat. No. 5,326,687 and U.S. Pat. No.5,624,467). Texter describes a process by which pyrazolone oxonol dyesare microprecipitated under strictly controlled pH conditions to produceabsorbance spectra which are narrow, bathochromic and sharp cutting onthe long wavelength side relative to their corresponding milled solidparticle dispersions. This technique, however, is impractical for largevolume applications.

A specific class of dyes, barbituric acid oxonol dyes, have beendisclosed in commonly assigned copending U.S. application Ser. No.08/565,480 filed Nov. 30, 1995, the entire disclosures of which areincorporated herein by reference, and U.S. Pat. No. 5,766,834 to possesssharp-cutting spectral properties when incorporated into gelatincoatings; however no reference is made to suggest that other filter dyeclasses might possess these useful spectral features. Further, thespectral features of these dyes are limited to a few specific wavelengthranges, and the hue of these sharp-cutting dyes are not tunable over alarge useful range.

It would be very useful if dye materials were available that werenon-wandering, like solid particle dispersions, but were additionallynarrowly absorbing and sharp-cutting in spectral features, like fullysolvent-soluble dyes, and were additionally available at a wide varietyof absorbance maxima useful in imaging elements.

PROBLEM TO BE SOLVED BY THE INVENTION

It is therefore desirable to have a dye, especially a filter dye, whichhas a high extinction coefficient, a narrow halfbandwidth, and is sharpcutting on the bathochromic and/or hypsochromic edge, and even morepreferably on both the hypsochromic and bathochromic edges. For dyesused in photographic elements, it is additionally desirable that the dyeis capable of being substantially completely removed or renderedcolorless on process of an exposed radiationsensitive element comprisingsaid dye. It is also desirable that the coated dye be robust in itsspectral and physical properties and not prone to migration within theimaging element. It is also desirable to have a method for preparing adispersion of a filter dye that is suitable for high-volume manufacture.

SUMMARY OF THE INVENTION

It has now been discovered that a set of oxonol dye classes may befunctionalized with certain substituents, and dispersed in hydrophiliccolloids to form lyotropic (solvent-induced) liquid-crystalline dyephases (mesophases). These mesophase-forming dyes possess unique anduseful properties superior to those of conventional water orsolvent-soluble dyes or solvent-insoluble solid particle dyes withrespect to hue, spectral shape, immobility, robustness and processremovability. Additionally it has been discovered that for a given dyeclass, one skilled in the art can optimize dye analogs such that theypossess an inherent propensity to form stable liquid-crystalline phasesrather than microcrystalline (solid) or isotropic (e.g. solution) phaseswhen dispersed in solvents, including hydrophilic colloids such asaqueous gelatin. Additionally it has been discovered that modificationsin the properties of the hydrophilic colloid dye dispersion, such asionic strength, temperature and pH can improve a given dye's propensityto form a stable liquid-crystalline phase. Additionally it has beendiscovered that the advantageous spectral and physical properties of thedye liquid crystalline phases formed in the wet hydrophilic colloid(e.g. aqueous gelatin) are largely retained in the dried-down(evaporated) gelatin coatings of an imaging element.

This invention relates specifically to amphiphilic dyes, especiallyfilter dyes in photographic elements which are capable of formingpractically useful lyotropic liquid-crystalline phases, particularlydyes from the thiphene dioxide oxonol classes.

Liquid-crystalline filter dyes afford a host of benefits overconventional state-of-the-art solid particle(microcrystalline)-incorporated dyes or water-soluble (isotropicsolution) filter dyes, for photographic imaging applications. Moreover,they provide a combination of spectral and physical properties that isvirtually unachievable using either water-soluble or solid particledyes. The following beneficial spectral and physical properties areinherent to the liquid-crystalline form of the dye. For example, dyesdispersed in a lyotropic liquid-crystalline form exhibit slow collectivemolecular diffusion (orders of magnitude slower than dye isotropicsolution species) affording good layer specificity and immobility, like(microcrystalline) solid particle dyes and unlike unmordanted isotropicsolution dyes. Dyes dispersed in a lyotropic liquid-crystalline formexhibit significantly higher extinction coefficients than(microcrystalline) solid particle dyes dispersed at equivalent wetlaydowns (concentrations). Dyes dispersed in a lyotropicliquid-crystalline form show processing washout and bleaching ratescomparable to, but usually much better than, conventional(microcrystalline) solid particle dyes. Lyotropic liquid-crystalline dyephases are more easily, rapidly and reproducibly formulated than(microcrystalline) solid particle dye phases. Dyes dispersed in alyotropic liquid-crystalline form, (especially the smectic mesophaseform), often exhibit sharper-cutting, more intense spectral absorptionfeatures than their (microcrystalline) solid particle counterparts,making them particularly useful as photographic finger filters. Dyesdispersed in a lyotropic liquid-crystalline form often exhibitcharacteristic bathochromically-shifted excitonic absorption J-bands(sharp, narrow and intense), possessing (long-wavelength) sharp-cuttingspectral features, making them particularly useful for many photographicfinger-filter applications. So-called J-band (J-aggregate) spectra arenot readily afforded by (microcrystalline) solid particle dyes. Dyesdispersed in a lyotropic liquid-crystalline form may also exhibitpractically useful hypsochromically-shifted H-band absorption spectra,with (short-wavelength) sharp-cutting spectral features. Dyes dispersedin a lyotropic liquid-crystalline state may also exhibit little or nospectral shift compared with the dye's isotropic solution absorbancestate, yet still retain the characteristic immobility of the liquidcrystalline phase. The essentially “immobile” lyotropicliquid-crystalline form (phase) of the preferred amphiphilic filterdyes, exhibiting characteristic and practically useful J-band and H-bandabsorption spectra, are quite distinct, easily identifiable and readilydistinguishable from non-liquid-crystalline (isotropic)rapidly-diffusing dye phases which occasionally exhibit similarabsorption spectra. Dyes dispersed in a lyotropic liquid-crystallinestate in aqueous, or those dyes passing through a transitory mesophaseupon the drying of aqueous gelatin layers, usually retain the usefulspectral and physical properties associated with the mesophase in theevaporated (dried-down)state. Dyes initially dispersed as a lyotropicliquid-crystalline form often exhibit good incubation stability inevaporated gelatin layers.

This invention comprises a set of oxonol dye classes, derived fromthiophene dioxide nuclei, which can form liquid crystals whenselectively functionalized as described below. This disclosure furtherteaches one skilled in the art how to find liquid-crystalline members ofa given dye class; it further includes test protocol for determining thepresence of a dye mesophase (i.e. liquid crystal phase), and shows thesuperior features dye liquid crystals possess compared with solidparticle dyes or solvent-soluble (solution) dyes. This invention furtherdemonstrates the advantages of dye mesophase properties in imagingelements, especially photographic elements.

One aspect of this invention comprises a filter dye which when dispersedin a solvent, especially water or a hydrophilic colloid such as aqueousgelatin, forms a liquid-crystalline phase.

Another aspect of this invention comprises a filter dye which whendispersed in a solvent or a hydrophilic colloid such as aqueous gelatin,forms a smectic liquid-crystalline phase.

Another aspect of this invention comprises a filter dye which whendispersed in a solvent or a hydrophilic colloid such as aqueous gelatin,forms a nematic or hexagonal liquid-crystalline phase.

Another aspect of the invention comprises a dye lyotropicliquid-crystalline which exhibits a spectral absorbance maximumbathochromically or hypsochromically shifted, and exhibits an unusuallyhigh extinction coefficient and an exceptionally narrow halfbandwidthrelative to its isotropic monomeric solution state.

Another aspect of this invention comprises a filter dye which whendispersed in a hydrophilic colloid such as aqueous gelatin to form aliquid-crystalline phase, possesses a narrow spectral absorption bandexhibiting an especially sharp-cutting short or long wavelength edge.

Another aspect of this invention comprises a filter dye which whendispersed in a hydrophilic colloid such as aqueous gelatin to form aliquid-crystalline phase, possesses a narrow spectral absorption bandexhibiting especially sharp-cutting short and long wavelength edges.

Another aspect of this invention comprises a filter dye which whendispersed in a hydrophilic colloid such as aqueous gelatin to form aliquid-crystalline phase, exhibits low dye diffusibility and interlayerwandering.

Another aspect of this invention comprises a direct gelatin dispersionmethod allowing easy, inexpensive, rapid and reproducible incorporationof the inventive dyes in the liquid-crystalline state, with alldesirable properties intact, into imaging elements, especiallyphotographic elements without recourse to milling techniques.

Another aspect of this invention comprises a filter dye which whendispersed in a hydrophilic colloid such as aqueous gelatin to form aliquid-crystalline phase exhibits excellent stability at hightemperature and humidity conditions.

Another aspect of this invention comprises a filter dye which whendispersed in a wet hydrophilic colloid such as aqueous gelatin to form aliquid crystalline phase retains all of the desirable physical andspectral properties once the coated imaging element is dried-down(evaporated).

Another aspect of the invention comprises a silver halideradiation-sensitive material containing at least one dye in theliquid-crystalline state, dispersed in a hydrophilic colloid layer,which is decolorized by photographic processing and which causes nodeleterious effects on the silver halide photographic emulsions beforeor after processing.

A further aspect of the invention comprises a silver halideradiation-sensitive material in which a hydrophilic colloid layer isdyed and exhibits excellent decolorizing properties upon photographicprocessing.

Yet another aspect of the invention comprises a silver halideradiation-sensitive material in which a hydrophilic colloid layer isdyed and exhibits high absorbance in a portion of the spectral region atits absorbance maximum, but possesses comparatively little absorbancearound 20 nm above its absorbance maximum.

Yet another aspect of the invention comprises a silver halideradiation-sensitive material in which a hydrophilic colloid layer isdyed and exhibits high absorbance in a portion of the spectral region atits absorbance maximum, but possesses comparatively little absorbancearound 20 nm below its absorbance maximum.

We have now discovered that certain dyes set forth below form stableliquid-crystalline phases when dispersed in wet aqueous media(preferably containing a hydrophilic colloid such as gelatin) andprovide the advantages set for in the above objects of the invention.The said liquid-crystalline dye dispersion can be formed by dispersingpowdered dye or a milled dye slurry into an aqueous medium, preferablycontaining gelatin or other hydrophilic colloid, over a specifiedconcentration and temperature range, using the methods set forth herein.

One aspect of this invention comprises an aqueous dispersion comprisingan aqueous medium having dispersed therein a liquid-crystal forming dyeof structural Formula I, II or III:

wherein Q¹ and Q² represent the non-metallic atoms required to form asubstituted or unsubstituted 5 or a 6-membered heterocyclic orcarbocyclic ring, preferably a substituted or unsubstituted aromatic orheteroaromatic ring including any fused polycyclic moeity, L¹ to L⁷ aresubstituted or unsubstituted methine groups, (including the possibilityof any of them being members of a five or six-membered ring where atleast one and preferably more than one of p, q, or r is 1); M⁺ is acation, and p, q and r are independently 0 or 1.; or a liquid-crystalforming dye of Formula II:

wherein R¹ to R⁴ each individually represent amino, alkylamino,dialkylamino, hydroxy, alkylthio, halogen, cyano, alkylsulfone,arylsulfone, or substituted or unsubstituted alkyl, aryl, heteroaryl, oraralkyl, and L¹ to L⁷, M⁺, and p, q and r are defined as described abovefor Formula I; or preferably a liquid-crystal forming dye of FormulaIII:

wherein R⁵ to R¹² each independently represents hydrogen, substituted orunsubstituted alkyl, or cycloalkyl; alkenyl, substituted orunsubstituted aryl, heteroaryl or aralkyl; alkylthio, hydroxy,hydroxylate, alkoxy, amino, alkylamino, halogen, cyano, nitro, carboxy,acyl, alkoxycarbonyl, aminocarbonyl, sulfonamido, sulfamoyl, or groupscontaining solubilizing substituents as described above for Y. Anyadjacent pair of substituents among R⁵ through R¹² may together form afused carbocyclic or heterocyclic aromatic or aliphatic ring. L¹ throughL⁷ are methine groups as described above, M⁺ is a cation, and p, q and rare independently 0, or 1 as described above; and the resulting dye ofFormulae I, II or III forms a liquid-crystalline phase in solvent suchas an aqueous media, including hydrophilic colloids, when dispersed asdescribed herein. Protocol for determining the presence ofliquid-crystalline phases is also described herein.

Useful dye include those absorbing in the UV region (below 400 nm), thevisible region (400-700 nm), and the infrared region (above 700 nm).

Another preferred embodiment of the invention comprises an imagingelement containing a liquid crystal-forming dye of structural Formula I,II, or III.

Still another preferred embodiment of the invention comprises aradiation-sensitive element, such as a photographic element, containinga liquid-crystal forming dye of structural Formula 1, II or III.

Yet another preferred embodiment of the invention comprises a method ofpreparing a liquid-crystalline dye dispersion which comprises adding adye of structural Formulae I-III to an aqueous medium at a temperatureof from about 2° C. to about 100° C. and agitating the mixture for about5 minutes to about 48 hours.

ADVANTAGEOUS EFFECTS OF THE INVENTION

This invention provides a dye, useful as a filter dye or light-absorbingcompound in an imaging element, and especially in a radiation-sensitiveelement, such as a photographic element, which when dispersed in anaqueous medium, for example aqueous gelatin, dissolves thenspontaneously forms a lyotropic liquid-crystalline phase whichconstitutes an unusually well-ordered and thermodynamically stable dyestate. A dye in the liquid-crystalline state often possesses a coatedλ_(max) which is substantially bathochromic or hypsochromic to that ofits monomeric isotropic solution (non-liquid crystalline) state andexhibits exceptionally high covering power at its coating λ_(max),Further, the liquid-crystalline dye phase often exhibits sharp-cuttingbathochromic and/or hypsochromic spectral features absorbing strongly atits coating λ_(max), while absorbing comparatively little light atwavelengths just below or just above its absorbance maximum. Further,the liquid-crystalline dye phase often possesses an unusually narrowhalfbandwidth. The dyes of this invention can be formulated forincorporation into a photographic element using, for example,conventional ball-mill or media-mill procedures for producing dyedispersions (SPD's), or more simply as direct gelatin dispersions(DGD's) for incorporation in a photographic element, as discussed morefully below. In the photographic element, dyes in thespontaneously-formed liquid-crystalline state exhibit little, if anytendency to wander, and upon processing many are substantially free ofpost-process stain problems.

DETAILED DESCRIPTION OF THE INVENTION

As noted above, the dispersion of this invention comprises aliquid-crystal forming dye of Formula I:

wherein Q¹ and Q² represent the non-metallic atoms required to form asubstituted or unsubstituted 5 or a 6-membered heterocyclic orcarbocyclic ring, preferably a substituted or unsubstituted aromatic orheteroaromatic ring including any fused polycyclic moeity, L¹ to L⁷ aresubstituted or unsubstituted methine groups, (including the possibilityof any of them being members of a five or six-membered ring where atleast one and preferably more than one of p, q, or r is 1); M⁺ is acation, and p, q and r are independently 0 or 1; or a dye of Formula II:

wherein R¹ to R⁴ each individually represent amino, alkylamino,dialkylamino, hydroxy, alkylthio, halogen, cyano, alkylsulfone,arylsulfone, or substituted or unsubstituted alkyl, aryl, heteroaryl, oraralkyl, and L¹ to L⁷, M⁺, and p, q and r are defined as described abovefor Formula I; and the resulting dye of Formulae 1 or 2 forms aliquid-crystalline phase in solvent such as an aqueous media, includinghydrophilic colloids, when dispersed as described herein. Protocol fordetermining the presence of liquid-crystalline phases is also describedherein.

Useful dye include those absorbing in the UV region (below 400 nm), thevisible region (400-700 nm), and the infrared region (above 700 nm).

In a preferred embodiment of the invention, the liquid-crystal formingdye of Formula II is an oxonol dye of Formula III:

wherein R⁵ to R¹² each independently represents hydrogen, substituted orunsubstituted alkyl, or cycloalkyl; alkenyl, substituted orunsubstituted aryl, heteroaryl or aralkyl; alkylthio, bydroxy,hydroxylate, alkoxy, anino, alkylamino, halogen, cyano, nitro, carboxy,acyl, alkoxycarbonyl, aminocarbonyl, sulfonamido, sulfamoyl,carboxylate, acylsulfonamido, sulfo, sulfonate, or alkylammonium. Anyadjacent pair of substituents among R⁵ through R¹² may together form afused carbocyclic or heterocyclic aromatic or aliphatic ring. L¹ throughL⁷ are methine groups as described above, M⁺ is a cation, and p, q and rare independently 0, or 1 as described above.

Still another preferred embodiment of the invention comprises an imagingelement containing a liquid crystal-forming dye of structural FormulaeI-III.

Still another preferred embodiment of the invention comprises aradiation-sensitive element, such as a photographic element, containinga liquid-crystal forming dye of structural Formulae I-III.

In Formulae I to III, M⁺ is a cation such as H⁺, Et₃NH⁺, C₅H₅NH⁺, Na⁺,and K⁺. “Group” wherever used in the present application includes thepossibility of being substituted or unsubstituted.

Q¹ and Q² may represent the non-metallic atoms required to form at leastone 5- or 6-membered aromatic ring. Examples of these fused ringsinclude pyridine, benzene, furan, pyrrole, thiophene and indole.

Methine groups may be substituted with, for example, an alkyl, alkenyl,aryl, aralkyl, cycloalkyl, or heterocyclic group or, as mentioned above,if more than one of p, q, or r is 1, two or more methine groups togetherwith their substituents may form a 5- or 6-membered carbocyclic orheterocycllic ring.

In general, when reference in this application is made to a particularmoiety or group it is to be understood that such reference encompassesthat moiety whether unsubstituted or substituted with one or moresubstituents (up to the maximum possible number). For example, “alkyl”or “alkyl group” refers to a substituted or unsubstituted alkyl, while“benzene group” refers to a substituted or unsubstituted benzene (withup to six substituents). Generally, unless otherwise specificallystated, substituent groups usable on molecules herein include anygroups, whether substituted or unsubstituted, which do not destroyproperties necessary for the photographic utility. Examples ofsubstituents on any of the mentioned groups can include knownsubstituents, such as: halogen, for example, chloro, fluoro, bromo,iodo; hydroxy; alkoxy, particularly those “lower alkyl” (that is, with 1to 6 carbon atoms, for example, methoxy, ethoxy; substituted orunsubstituted alkyl, particularly lower alkyl (for example, methyl,trifluoromethyl); thioalkyl (for example, methylthio or ethylthio),particularly either of those with 1 to 6 carbon atoms; substituted orunsubstituted alkenyl, preferably of 2 to 10 carbon atoms (for example,ethenyl, propenyl, or butenyl); substituted and unsubstituted aryl,particularly those having from 6 to 20 carbon atoms (for example,phenyl); and substituted or unsubstituted heteroaryl, particularly thosehaving a 5 or 6-membered ring containing 1 to 3 heteroatoms selectedfrom N, O, or S (for example, pyridyl, thienyl, furyl, pyrrolyl); acidor acid salt groups such as any of those described below; hydroxylate,amino, alkylamino, cyano, nitro, carboxy, carboxylate, acyl,alkoxycarbonyl, aminocarbonyl, sulfonamido, sulfamoyl, sulfo, sulfonate,and alkylammonium; and others known in the art. Alkyl substituents mayspecifically include “lower alkyl” (that is, having 1-6 carbon atoms),for example, methyl, ethyl, and the like. Further, with regard to anyalkyl group or alkylene group, it will be understood that these can bebranched or unbranched and include ring structures.

Examples of preferred dyes of the invention are listed below.

TABLE 1

Dye R² R³ R⁴ R⁵ M⁺ 1-1 H H Cl H H 1-1A H H Cl H TEAH 1-2 H H F H H 1-2AH H F H TEAH 1-3 H OMe H H H 1-4 Cl H H Cl TEAH 1-5 H Me H H TEAH 1-6 MeH H H H 1-7 H H Ph H TEAH 1-7A H H Ph H Na 1-8 H Cl H H H 1-9 H Ac H H H1-10 H Ac Cl H Pyr 1-11 H OH H H H 1-12 H H OH H TEAH 1-13 H H Br H Pyr1-14 H OMe Cl H TEAH 1-15 H H H F H 1-16 H NHAc —H H H 1-17 H Cl Me HTEAH 1-17A H Cl Me H H 1-18 H H COOEt H Na 1-19 H Me H H Pyr 1-20 H OHOH H H

TABLE II

R¹ R² R³ R⁴ R⁵ M⁺ 2-1 H H H Cl H H 2-1A H H H Cl H TEAH 2-2 H Me H F HTEAH 2-3 H H OMe H H H 2-4 H H Me H H H 2-5 H H H H Cl H 2-6 H H OMe OMeH H 2-7 H H H Ph H Na 2-8 H H Cl H H H 2-9 H H Ac H H H 2-10 H H H COOEtH Na 2-11 Me H H Cl H TEAH 2-11A Me H H Cl H H 2-12 H H Me H H TEAH 2-13Me H Me H H TEAH 2-14 H H OH H H H 2-15 H H H OH H TEAH

TABLE III

Dye R¹ R² R³ R⁴ R⁵ M⁺ 3-1 Me H OMe OMe H H 3-1A Me H OMe OMe H TEAH 3-2H H H Cl H H 3-3 H H OH H H TEAH 3-4 Me H OH H H TEAH 3-5 Et H H OMe H H3-6 Me H H Ph H Na 3-7 Me H H F H TEAH

The dyes of Formulae I-III can be prepared by synthetic techniqueswell-known in the art, as illustrated by the synthetic examples below.Such techniques are further illustrated, for example, in “The CyanineDyes and Related Compounds”, Frances Hamer, Interscience Publishers,1964.

The liquid-crystalline dye dispersions of this invention may be preparedby well-known methods commonly employed for preparing solid particle dyedispersions. Here, a slurry of the dye in an aqueous medium comprisingwater and a surfactant or water-soluble polymer is subjected to amilling procedure such as ball-milling, sand-milling, media-milling orcolloid-milling (preferably media-milling). The dye slurry can then bemixed with aqueous gelatin at an appropriate concentration (preferably≦30% w/w) and at a temperature (preferably 20 to 90° C.)for use in aphotographic element.

In another preferred embodiment, the liquid-crystalline dye dispersionsof this invention may be prepared using a direct gelatin dispersion(DGD) method wherein the finely powdered dye or aqueous slurry thereofis simply mixed or agitated with water or with an aqueous mediumcontaining gelatin (or other hydrophilic colloid) at an appropriateconcentration (preferably ≦30% w/w) and at a temperature (preferably 0to 100° C.).

In either of the preferred methods, the dyes may be subjected toelevated temperatures before and/or after gelatin dispersion, but toobtain desirable results, this heat treatment is carried out preferablyafter dispersing in gelatin. The optimal temperature range for preparinggelatin-based dispersions is 20° C.-100° C., depending on theconcentration of the gelatin, but should remain below the decompositionpoints of the dyes, and, preferably for the range of 5 minutes to 48hours. A similar heat treatment may be applied, if so desired, to dyesprepared by milling methodsas solid particle dispersions before and/orafter dispersion in aqueous gelatin to obtain effective results.Furthermore, if so desired, pH and/or ionic strength and solventcomposition adjustments, for example, may be utilized to control thesolubility and liquid crystal-forming properties of dyes prepared usingSPD or DGD formulation techniques. The direct gelatin dispersion methodis advantageous in that it does not necessarily require the use oforganic solvents, surfactants, polymer additives, electrolytes, millingprocesses, pH control or the like. It is generally simpler, faster, moreforgiving and more flexible than milling processes. A related methoddescribed by Boettcher for preparing concentrated sensitizing dyedispersions in aqueous gelatin (PCT WO 93/23792) is equally effectivewhen applied to the inventive dyes. The entire disclosure of WO 93/23792is incorporated herein by reference. The inventive lyotropicliquid-crystalline dye dispersions may be incorporated directly intoimaging elements.

Solid particle dispersion and direct gelatin dispersion formulations ofthe compound of Formula (I-III) are useful as general purpose filterdyes, alone or in combination with other filter dyes in photographicelements. The dyes formulated as described above possess a pronouncedtendency to form liquid crystal phases spontaneously at a variety ofpH's, including typical coating pH's of 6 or less (generally 4-6) suchthat they do not substantially wander from the layer in which they arecoated. However, they are highly soluble at processing pH's of 8 or more(generally 8-12), such that they are often still fully removed duringphotographic processing.

Our invention comprises a set of oxonol dye classes which arefunctionalized to form liquid crystalline phases in solvents, especiallywater, and hydrophilic colloids such as aqueous gelatin. These materialswould be especially useful as filter dyes in photographic systems asdescribed above, as spectral sensitizers, and in non-photographicimaging applications such as inkjet, barcoding, and thermally-developedimaging systems.

There are few teachings addressing dye lyotropic liquid-crystallinephases. Additionally, no teachings are provided that would enable oneskilled in the art to design and synthesize dyes capable of formingliquid crystals or to influence their formation in imaging elements.

For most materials, it is generally accepted that only three states ofmatter exist; namely, solids, liquids and gases. However, some materialsexhibit a fourth state of matter commonly referred to as a liquidcrystal phase (or mesophase). Liquid crystal phases are neithercrystalline solids nor isotropic liquids, but exhibit some of thecharacteristics of both. A liquid crystal phase can be described simplyas being a liquid with a certain degree of molecular order. As describedbelow, this molecular order gives rise to measurable anisotropy in thebulk properties of a material that is otherwise much like a liquid.Consequently, the physical properties of liquid-crystalline materialsare unique and distinct from those of solids and liquids. Thesedifferences can be utilized to advantage in the formulation ofphotographic elements and also allow detection of the liquid crystalphase by a variety of optical and spectroscopic techniques.

Liquid crystals can be classified as thermotropic or lyotropic. The dyecompositions of the current invention are of the lyotropic type,however, for puposes of comparision, we first give a brief descriptionthe thermotropic type: Some crystalline compounds do not yield anisotropic liquid immediately upon melting, instead, the newly formed“melt” is a liquid crystal phase (mesophase). In the simple cases,further heating results in the formation of an ordinary isotropicliquid. The phase that exists above the melting point of the crystallinesolid but below the formation temperature for the isotropic liquid isknown as a thermotropic liquid crystal phase. In some cases, heating theinitally formed mesophase does not result in an isotropic liquid, butrather, to one or more intermediate liquid crystal phases, and finally,the last formed of these, upon further heating, yields the isotropicliquid. All of the mesophases formed in this way are conventionallyclassified as thermotropic. The term thermotropic liquid crystal is alsoextended to include eutectic mixtures of compounds. Thermotropic liquidcrystals are generally colorless organic materials and are typicallyhydrophobic (water-insoluble) in character. They are commonly employedin electro-optical display devices, for example digital watches andcalculators.

In contrast, spontaneous formation of lyotropic liquid crystals can beachieved at a fixed temperature by simple addition of a solvent to asuitable solute (mesogen). The solvent is typically (but notnecessarily) water and lyotropic mesophases are stable over finiteranges of both concentration and temperature. Typical lyotropic mesogensare amphiphilic. The term amphiphilic acknowledges that both hydrophobicgroups (e.g. aliphatic, aromatic, etc.) and hydrophilic groups (e.g. CO₂⁻M⁺, SO₃ ⁻M⁺, SO₄ ⁻M⁺, O(CH₂CH₂O)_(x), etc.) are present on the samemolecule. Examples include, surfactants, lipids, polymers, dyes, anddrugs. The amphiphilic nature and the specific hydrophilic-hydrophobicbalance (HHB) of these molecules influences their tendency to formlyotropic mesophases.

The structural type(s) and stability with respect to concentration andtemperature of the liquid crystalline phase(s) formed are highlymesogen-dependent. For example, Koll et al. (U.S. Pat. No. 4,309,183,Jan. 5, 1982) teach how a lyotropic liquid-crystalline phase of aparticular anionic azo reactive dyestuff can be prepared in water atroom temperature and dye concentrations of 12-35%, for the specific useof dyeing and printing natural and synthetic substrates. However, noreference to such dyes for use in imaging elements has been reported.

It is part of the purpose of this invention to demonstrate thatthiophenedioxide oxonol chromophores can and do form lyotropic liquid crystalsupon suitable manipulation of substituents. It is a further purpose ofthis work to provide some examples of substituent combinations that areeffective in trasforming a quite ordinary set of oxonol dyes classes,that is to say, dye classes for which mesophases have never beenreported, into photographically useful lyotropic mesogens.

In the preferred embodiment, the amphiphilic filter dye will form anyliquid-crystalline phase upon dispersing said dye in the hydrophilicsolvent medium, typically, but not limited to, water or aqueous gelatin,at the wet laydown (dye concentration) and temperature of choice(preferably □30% w/w dye, more preferably ≦10% w/w dye, even morepreferably ≦5% w/w dye and most preferably ≦0.5% w/w dye, between 0° C.and 100° C.). In the most preferred embodiment, said dye mesophase willpossess a layered smectic structure, and in another preferred embodimentthe dye mesophase will possess a nematic or hexagonal structure. We havediscovered that the liquid-crystalline phase stability of lyotropicamphiphilic (particularly ionic) filter dyes may also be sensitive tothe presence of addenda such as gelatin of different types, polymers,organic solvents (such as alcohols, acetone etc.) and surfactants. Forexample, low-levels of common electrolytes can stabilize ionic dyemesophase formation. Enhanced mesophase stability of ionic filter dyes(with respect to both temperature and concentration) may be realizedsimply by the judicious choice of photographic gelatin (e.g. so-calledregular, deionized or decalcified gelatin grades) which containdifferent levels and types of electrolyte cations and anions (e.g.calcium, magnesium, sodium, chloride, sulphate etc.) as a by-product ofgelatin manufacture. Similarly, the use of non-deionized water or theaddition of low salt levels to purified (deionized or distilled) water,can afford enhanced mesophase stability for certain ionic filter dyes.The preferred dyes of this invention are chosen to exhibit stablelyotropic mesophases under the practical conditions generally employedfor their formulation, dispersion, coating and drying. It is understoodthat someone skilled in the art of dyes could, with the guidanceprovided in this disclosure, systematically optimize dye structureand/or solvent conditions to enhance and control dye mesophase formationand stability for a suitable mesogen-solvent combination.

Since mesophase formation is both concentration and temperaturedependent, it is understood that some of the preferred amphiphilicfilter dyes may initially form an isotropic solution phase which willundergo a transition to a more concentrated and thermally-stablemesophase during the drying process (thermal stability of dye mesophasesinvariably increases with dye mesophase concentration).

Some of the preferred amphiphilic filter dyes initially dispersed in thewet hydrophilic colloid medium (e.g. aqueous gelatin) as a diluteliquid-crystalline dye phase, may remain wholly liquid-crystalline upondrying or undergo a (for example, concentration-dependent or ionicstrength-dependent) reversible transition from the liquid-crystallinestate to a crystalline, semi-crystalline, or amorphous solid dye state,or a mixture thereof, during the drying process. However, we have foundthat in such instances the preferred dyes still largely retain theuseful spectral and physical properties associated with the originallydispersed dilute dye mesophase (e.g. absorption envelope providing goodcovering power, layer specificity, incubation stability, rapidprocessing elution and or bleachability). The final physical form of thegelatin-dispersed dye (liquid-crystalline, crystalline, amorphous solid)will depend on the precise phase behaviour of said dye in relation tothe retained moisture (water) content of the evaporated (dried-down)gelatin film under given conditions of temperature and humidity and thepresence of other solutes. However, according to the invention, dyeswhich remain liquid crystalline when formulated and dispersed in thephotographic vehicle, or those which pass through a transitoryliquid-crystalline phase at any stage during the subsequent coating anddrying process, will afford the useful and unique combination of bothspectral and physical properties, described herein. It should beemphasized that reference in this disclosure to “evaporated” or “dried”coatings refers to coatings of wet aqueous gelatin melts from whichexcess water or solvent has been allowed to evaporate or has beenremoved by drying processes, but which still retain an equilibriummoisture level typical of finished imaging elements especiallyphotographic imaging elements.

According to the invention, the preferred dye chromophores must possesssome added degree of hydrophilicity, imparted by ionic, zwitterionic ornonionic solubilizing groups, to be capable of forming lyotropicliquid-crystalline phases in aqueous-based media. Similarly, if sodesired, for non-aqueous (e.g. organic) solvent applications, the dyeshould possess additional hydrophobic, rather than hydrophilic,solubilizing moieties, such as branched aliphatic chains.

Common mesophase structural types, such as layered smectic (e.g.lamellar), columnar hexagonal and nematic, which possess varying degreesof orientational & translational molecular order, may be formed by manydiverse and disparate lyotropic mesogens. Because of the inherentordered nature of these anisotropic, thermodynamically stable,supramolecular structures, experimental techniques including, forexample, small-angle X-ray (or neutron) scattering, polarized-lightoptical microscopy and quadrupole (e.g. ²³Na, ²H, ¹⁷O, ¹⁴N etc.) NMRspectroscopy may be routinely applied to identifying and characterizingthe structure and physico-chemical properties of lyotropic mesophases.

According to the invention, the preferred dyes can be readily identifiedusing the technique of polarized-light optical microscopy (as describedby N. H. Hartshorne in, “The Microscopy of Liquid Crystals”, MicroscopePublications Ltd., London, England, 1974). In order to ascertain theexact quantitative mesophase behaviour of a given dye-solventcombination, a range of sample mixtures of known composition areprepared (typically dyes dissolved in aqueous gelatin) and viewed inpolarized light as wet thin films (contained within sealed glasscapillary cells of known pathlength) and slowly-evaporated thin films(hand-coated onto glass microscope slides and air-dried) to establishthe precise concentration and temperature ranges of dye mesophasestability. These same thin-film preparations may also be used toelucidate and quantify the spectral absorption properties of the dyemesophase, such as absorption wavelength, bandwidth, extinctioncoefficient etc. using a uv-vis spectrophotometer.

Simple observations of the characteristic birefringent type-textures andrheology (flow behaviour under shear) displayed by thin-film mesophasepreparations in polarized light are usually sufficient to establish themesophase structural type (e.g. smectic, nematic, hexagonal dependingupon the specific long-range inter-aggregate ordering) as a function ofsolute-solvent concentration and temperature. Dyes forming lyotropicchromonic nematic mesophases may be identified from a range of fluid,viscoelastic textures including so-called Schlieren, Tiger-Skin,Reticulated, Homogeneous (Planar), Thread-like, Droplet and Homeotropic(Pseudoisotropic). Lyotropic chromonic hexagonal mesophases usuallydisplay viscous, birefringent Herringbone, Ribbon or Fan-like textureswhile lyotropic chromonic smectic mesophases may display Grainy-Mosaic,Frond-like (Pseudo-Schlieren), Spherulitic and Oily-Streak birefringenttextures. In some cases where the liquid-crystalline nature of thesample cannot be established unequivocally using polarized-light opticalmicroscopy other well-established experimental techniques may beutilized. For example, lyotropic mesophases exhibit characteristicquadrupole NMR spectroscopy lineshapes and quadrupole splittings, whilesmall-angle and wide-angle X-ray (or neutron) diffraction measurementsprovide unique and characteristic structured diffraction patterns (referto “Liquid Crystals and Plastic Crystals”, eds. G. W. Gray & P. A.Winsor, Ellis Horwood Ltd., Chichester, UK, 1974, Vols. 1 and 2). Suchphase-dependent properties may be used to differentiate, for example, aliquid-crystalline filter dye dispersion from a conventionalmicrocrystalline (ie.solid) filter dye dispersion.

A particular advantage of the inventive dyes is that in the liquidcrystalline state, they provide higher covering power at their coatingλ_(max) than comparable known dyes which are insoluble and exist asmicrocrystalline solid particles in the photographic medium. Thisadvantage is particularly important in modern film formats andprocessing conditions, as filter dyes with high covering power need notbe coated at as high a coverage as dyes with lower covering power inorder to achieve the same degree of light filtration. In addition toreducing manufacturing costs, lower levels of coated dyes will reducethe level of unwanted dye stain in the processed photographic element,and will reduce the level of dye residue built up in the processingsolutions, and the resulting lower levels of dissolved dye residueremoved from photographic elements will have reduced environmentalimpact.

A further advantage of dyes of the invention is that they generallypossess absorbance envelopes that are sharper cutting on thebathochromic side than typical solid particle dyes. This feature isespecially advantageous when strong light absorbance is required in aspectral region up to a specific λ_(max) and maximum light transmissionis required past the specified λ_(max). Such filter or trimmer dyes areespecially useful when coated in specific layers of color photographicfilms to effectively prevent light of a specific wavelength region fromexposing radiation-sensitive layers below the light filtration layercontaining the dye, but without causing speed losses in the layer belowthe filter dye. A green filter dye coated directly above a red-sensitivesilver halide layer is a particularly advantageous example of suchabsorbance features, and excellent green/red speed separation can berealized. A sharp-cutting bathochromic edge on a filter or trimmer dyeenables excellent color reproduction with minimum speed loss byabsorbing light efficiently up to its absorbance maximum, but verylittle if any just past its absorbance maximum. A magenta trimmer dye(green absorber) which is only moderately sharp-cutting on thebathochromic edge may function adequately as a filter dye, but itsunwanted absorbance in the red region past its λ_(max) will rob thered-sensitive emulsion coated below it of red light and hence speed.In atypical color photographic element, it is desirable to have agreen-absorbing filter dye which when coated absorbs strongly atwavelengths close to 550 nm, but which absorbs comparatively little atwavelengths greater than 550 nm. It should be emphasized that the exactenvelope of desirable light absorbance for a filter dye, evenspecifically a green filter dye, varies tremendously from onephotographic element to another depending on the intended purpose of thematerial. Some photographic elements might require a filter dye, such asa green filter dye, which absorbs strongly up to a wavelength somewhatshorter or longer than 550 nm, but is sharp cutting on the bathochromicside, mostly transmitting wavelengths of light past the desiredabsorbance λ_(max). The feature of coated dye absorbance exhibiting asharp cutting bathochromic and/or hypsochromic characteristic isfundamentally useful for wavelength-specific light filtration, thoughthe exact wavelength of desired spectral shift from absorbance totransmission may be different for different photographic materials.

A further advantage of the dyes of the invention is that in the liquidcrystalline state, many are much sharper absorbing than in theirdissolved isotropic solution state, that is, they possess a muchnarrower halfbandwidth. Furthermore, unlike a dye in the dissolved,isotropic solution state, the dye in the liquid-crystalline state isessentially immobile and not prone to gross diffusion and thus can becoated layer specifically.

The dyes may be located in any layer of the element where it isdesirable to absorb light, but in photographic elements it isparticularly advantageous to locate them in a layer where they will besolubilized and washed out during processing. Useful amounts of dyerange from 1 to 1000 mg/m². The dye should be present in an amountsufficient to yield an optical density at the absorbance D_(max) in thespectral region of interest before processing of at least 0.10 densityunits and preferably at least 0.50 density units. This optical densitywill generally be less than 5.0 density units for most photographicapplications.

The dyes of the invention can be used as interlayer dyes, trimmer dyes,antihalation dyes or light-absorbing elements. They can be used toprevent crossover in X-ray materials as disclosed in U.S. Pat. Nos.4,900,652 and 4,803,150 and European Patent Application Publication No.0 391 405, to prevent unwanted light from reaching a sensitive emulsionlayer of a multicolor photographic element as disclosed in U.S. Pat. No.4,988,611, and for other uses as indicated by the absorbance spectrum ofthe particular dye. The dyes can be used in a separate filter layer oras an intergrain absorber.

The liquid crystal-forming dyes of Formula (I-III) are useful for thepreparation of radiation sensitive materials. Such materials aresensitive to radiation such as visible light, ultraviolet, infrared, orX-ray.

The liquid crystal-forming dyes of Formula (I-III) are also useful innon-photographic imaging elements such as thermally-developableelements, or as dye materials for inkjet applications. Thenon-photographic imaging material may be an optical recording medium,such as a CD or other medium sensitive to a laser, light-emitting diode,or a thermally-developable material.

Another aspect of this invention comprises a radiation sensitive elementcontaining a liquid crystal-forming dye of Formula (I-III). Preferably,the radiation sensitive element is a photographic element comprising asupport bearing at least one light sensitive hydrophilic colloid layerand at least one other hydrophilic colloid layer. A dye of Formula I-IIImay be incorporated in a hydrophilic layer of the photographic elementin any known way.

The support of the element of the invention can be any of a number ofwell-known supports for photographic elements as discussed more fullybelow.

The photographic elements made by the method of the present inventioncan be single color elements or multicolor elements. Multicolor elementscontain dye image-forming units sensitive to each of the three primaryregions of the spectrum. Each unit can be comprised of a single emulsionlayer or of multiple emulsion layers sensitive to a given region of thespectrum. The layers of the element, including the layers of theimage-forming units, can be arranged in various orders as known in theart. In an alternative format, the emulsions sensitive to each of thethree primary regions of the spectrum can be disposed as a singlesegmented layer.

A typical multicolor photographic element comprises a support bearing acyan dye image-forming unit comprised of at least one red-sensitivesilver halide emulsion layer having associated therewith at least onecyan dye-forming coupler, a magenta dye image-forming unit comprising atleast one green-sensitive silver halide emulsion layer having associatedtherewith at least one magenta dye-forming coupler, and a yellow dyeimage-forming unit comprising at least one blue-sensitive silver halideemulsion layer having associated therewith at least one yellowdye-forming coupler. The element can contain additional layers, such asfilter layers, interlayers, overcoat layers, subbing layers, and thelike. All of these can be coated on a support which can be transparentor reflective (for example, a paper support).

Photographic elements of the present invention may also usefully includea magnetic recording material as described in Research Disclosure, Item34390, November 1992, or a transparent magnetic recording layer such asa layer containing magnetic particles on the underside of a transparentsupport as in U.S. Pat. No. 4,279,945 and U.S. Pat. No. 4,302,523. Theelement typically will have a total thickness (excluding the support) offrom 5 to 30 microns. While the order of the color sensitive layers canbe varied, they will normally be red-sensitive, green-sensitive andblue-sensitive, in that order on a transparent support, (that is, bluesensitive furthest from the support) and the reverse order on areflective support being typical.

The present invention also contemplates the use of photographic elementsof the present invention in what are often referred to as single usecameras (or “film with lens” units). These cameras are sold with filmpreloaded in them and the entire camera is returned to a processor withthe exposed film remaining inside the camera Such cameras may have glassor plastic lenses through which the photographic element is exposed.

In the following discussion of suitable materials for use in elements ofthis invention, reference will be made to Research Disclosure, September1996, Number 389, Item 38957, which will be identified hereafter by theterm “Research Disclosure I.” The Sections hereafter referred to areSections of the Research Disclosure I unless otherwise indicated. AllResearch Disclosures referenced are published by Kenneth MasonPublications, Ltd., Dudley Annex, 12a North Street, Emsworth, HampshireP010 7DQ, ENGLAND. The foregoing references and all other referencescited in this application, are incorporated herein by reference.

The silver halide emulsions employed in the photographic elements of thepresent invention may be negative-working, such as surface-sensitiveemulsions or unfogged internal latent image forming emulsions, orpositive working emulsions of internal latent image forming emulsions(that are either fogged in the element or fogged during processing).Suitable emulsions and their preparation as well as methods of chemicaland spectral sensitization are described in Sections I through V. Colormaterials and development modifiers are described in Sections V throughXX. Vehicles which can be used in the photographic elements aredescribed in Section II, and various additives such as brighteners,antifoggants, stabilizers, light absorbing and scattering materials,hardeners, coating aids, plasticizers, lubricants and matting agents aredescribed, for example, in Sections VI through XIII. Manufacturingmethods are described in all of the sections, layer arrangementsparticularly in Section XI, exposure alternatives in Section XVI, andprocessing methods and agents in Sections XIX and XX.

With negative working silver halide a negative image can be formed.Optionally a positive (or reversal) image can be formed although anegative image is typically first formed.

The photographic elements of the present invention may also use coloredcouplers (e.g., to adjust levels of interlayer correction) and maskingcouplers such as those described in EP 213 490; Japanese PublishedApplication 58-172,647; U.S. Pat. No. 2,983,608; German Application DE2,706,117C; U.K. Patent 1,530,272; Japanese Application A-113935; U.S.Pat. No. 4,070,191 and German Application DE 2,643,965. The maskingcouplers may be shifted or blocked.

The photographic elements may also contain materials that accelerate orotherwise modify the processing steps of bleaching or fixing to improvethe quality of the image. Bleach accelerators described in EP 193 389;EP 301 477; U.S. Pat. No. 4,163,669; U.S. Pat. No. 4,865,956; and U.S.Pat. No. 4,923,784 are particularly useful. Also contemplated is the useof nucleating agents, development accelerators or their precursors (U.K.Patent 2,097,140; U.K. Patent 2,131,188); electron transfer agents (U.S.Pat. No. 4,859,578; U.S. Pat. No. 4,912,025); antifogging and anticolor-mixing agents such as derivatives of hydroquinones, aminophenols,amines, gallic acid; catechol; ascorbic acid; hydrazides;sulfonamidophenols; and non color-forming couplers.

The elements may also contain filter dye layers comprising colloidalsilver sol or yellow and/or magenta filter dyes and/or antihalation dyes(particularly in an undercoat beneath all light sensitive layers or inthe side of the support opposite that on which all light sensitivelayers are located) formulated either as oil-in-water dispersions, latexdispersions, solid particle dispersions, or as direct gelatindispersions. Additionally, they may be used with “smearing” couplers(e.g., as described in U.S. Pat. No. 4,366,237; EP 096 570; U.S. Pat.No. 4,420,556; and U.S. Pat. No. 4,543,323.) Also, the couplers may beblocked or coated in protected form as described, for example, inJapanese Application 61/258,249 or U.S. Pat. No. 5,019,492.

The photographic elements may further contain other image-modifyingcompounds such as “Developer Inhibitor-Releasing” compounds (DIR's).Useful additional DIRs for elements of the present invention, are knownin the art and examples are described in U.S. Pat. Nos. 3,137,578;3,148,022; 3,148,062; 3,227,554; 3,384,657; 3,379,529; 3,615,506;3,617,291; 3,620,746; 3,701,783; 3,733,201; 4,049,455; 4,095,984;4,126,459; 4,149,886; 4,150,228; 4,211,562; 4,248,962; 4,259,437;4,362,878; 4,409,323; 4,477,563; 4,782,012; 4,962,018; 4,500,634;4,579,816; 4,607,004; 4,618,571; 4,678,739; 4,746,600; 4,746,601;4,791,049; 4,857,447; 4,865,959; 4,880,342; 4,886,736; 4,937,179;4,946,767; 4,948,716; 4,952,485; 4,956,269; 4,959,299; 4,966,835;4,985,336 as well as in patent publications GB 1,560,240; GB 2,007,662;GB 2,032,914; GB 2,099,167; DE 2,842,063, DE 2,937,127; DE 3,636,824; DE3,644,416 as well as the following European Patent Publications:272,573; 335,319; 336,411; 346, 899; 362, 870; 365,252; 365,346;373,382; 376,212; 377,463; 378,236; 384,670; 396,486; 401,612; 401,613.

DIR compounds are also disclosed in “Developer-Inhibitor-Releasing (DIR)Couplers for Color Photography,” C. R. Barr, J. R. Thirtle and P. W.Vittum in Photographic Science and Engineering, Vol. 13, p. 174 (1969),incorporated herein by reference.

It is also contemplated that the concepts of the present invention maybe employed to obtain reflection color prints as described in ResearchDisclosure, November 1979, Item 18716, available from Kenneth MasonPublications, Ltd, Dudley Annex, 12a North Street, Emsworth, HampshireP0101 7DQ, England, incorporated herein by reference. The emulsions andmaterials to form elements of the present invention, may be coated on pHadjusted support as described in U.S. Pat. No. 4,917,994; with epoxysolvents (EP 0 164 961); with additional stabilizers (as described, forexample, in U.S. Pat. No. 4,346,165; U.S. Pat. No. 4,540,653 and U.S.Pat. No. 4,906,559); with ballasted chelating agents such as those inU.S. Pat. No. 4,994,359 to reduce sensitivity to polyvalent cations suchas calcium; and with stain reducing compounds such as described in U.S.Pat. No. 5,068,171 and U.S. Pat. No. 5,096,805. Other compounds usefulin the elements of the invention are disclosed in Japanese PublishedApplications 83-09,959; 83-62,586; 90-072,629, 90-072,630; 90-072,632;90-072,633; 90-072,634; 90-077,822; 90-078,229; 90-078,230; 90-079,336;90-079,338; 90-079,690; 90-079,691; 90-080,487; 90-080,489; 90-080,490;90-080,491; 90-080,492; 90-080,494; 90-085,928; 90-086,669; 90-086,670;90-087,361; 90-087,362; 90-087,363; 90-087,364; 90-088,096; 90-088,097;90-093,662; 90-093,663; 90-093,664; 90-093,665; 90-093,666; 90-093,668;90-094,055; 90-094,056; 90-101,937; 90-103,409; 90-151,577.

The silver halide used in the photographic elements may be silveriodobromide, silver bromide, silver chloride, silver chlorobromide,silver chloroiodobromide, and the like. For example, the silver halideused in the photographic elements of the present invention may containat least 90% silver chloride or more (for example, at least 95%, 98%,99% or 100% silver chloride). In the case of such high chloride silverhalide emulsions, some silver bromide may be present but typicallysubstantially no silver iodide. Substantially no silver iodide means theiodide concentration would be no more than 1%, and preferably less than0.5 or 0.1%. In particular, in such a case the possibility is alsocontemplated that the silver chloride could be treated with a bromidesource to increase its sensitivity, although the bulk concentration ofbromide in the resulting emulsion will typically be no more than about 2to 2.5% and preferably between about 0.6 to 1.2% (the remainder beingsilver chloride). The foregoing % figures are mole %.

The type of silver halide grains preferably include polymorphic, cubic,and octahedral. The grain size of the silver halide may have anydistribution known to be useful in photographic compositions, and may beeither polydipersed or monodispersed.

Tabular grain silver halide emulsions may also be used. Tabular grainsare those with two parallel major faces each clearly larger than anyremaining grain face and tabular grain emulsions are those in which thetabular grains account for at least 30 percent, more typically at least50 percent, preferably >70 percent and optimally >90 percent of totalgrain projected area. The tabular grains can account for substantiallyall (>97 percent) of total grain projected area. The tabular grainemulsions can be high aspect ratio tabular grain emulsions—i.e.,ECD/t>8, where ECD is the diameter of a circle having an area equal tograin projected area and t is tabular grain thickness; intermediateaspect ratio tabular grain emulsions—i.e., ECD/t=5 to 8; or low aspectratio tabular grain emulsions—i.e., ECD/t=2 to 5. The emulsionstypically exhibit high tabularity (T), where T (i.e., ECD/t²)>25 and ECDand t are both measured in micrometers (mm). The tabular grains can beof any thickness compatible with achieving an aim average aspect ratioandlor average tabularity of the tabular grain emulsion. Preferably thetabular grains satisfying projected area requirements are those havingthicknesses of <0.3 mm, thin (<0.2 mm) tabular grains being specificallypreferred and ultrathin (<0.07 mm) tabular grains being contemplated formaximum tabular grain performance enhancements. When the native blueabsorption of iodohalide tabular grains is relied upon for blue speed,thicker tabular grains, typically up to 0.5 mm in thickness, arecontemplated.

High iodide tabular grain emulsions are illustrated by House U.S. Pat.No. 4,490,458, Maskasky U.S. Pat. No. 4,459,353 and Yagi et al EPO 0 410410.

Tabular grains formed of silver halide(s) that form a face centeredcubic (rock salt type) crystal lattice structure can have either {100}or {111} major faces. Emulsions containing {111} major face tabulargrains, including those with controlled grain dispersities, halidedistributions, twin plane spacing, edge structures and graindislocations as well as adsorbed {111} grain face stabilizers, areillustrated in those references cited in Research Disclosure I, SectionI.B.(3) (page 503).

The silver halide grains to be used in the invention may be preparedaccording to methods known in the art, such as those described inResearch Disclosure I and James, The Theory of the Photographic Process.These include methods such as ammoniacal emulsion making, neutral oracidic emulsion making, and others known in the art. These methodsgenerally involve mixing a water soluble silver salt with a watersoluble halide salt in the presence of a protective colloid, andcontrolling the temperature, pAg, pH values, etc, at suitable valuesduring formation of the silver halide by precipitation.

The silver halide to be used in the invention may be advantageouslysubjected to chemical sensitization with noble metal (for example, gold)sensitizers, middle chalcogen (for example, sulfur) sensitizers,reduction sensitizers and others known in the art. Compounds andtechniques useful for chemical sensitization of silver halide are knownin the art and described in Research Disclosure I and the referencescited therein.

The photographic elements of the present invention, as is typical,provide the silver halide in the form of an emulsion. Photographicemulsions generally include a vehicle for coating the emulsion as alayer of a photographic element. Useful vehicles include both naturallyoccurring substances such as proteins, protein derivatives, cellulosederivatives (e.g., cellulose esters), gelatin (e.g., alkali-treatedgelatin such as cattle bone or hide gelatin, or acid treated gelatinsuch as pigskin gelatin), gelatin derivatives (e.g., acetylated gelatin,phthalated gelatin, and the like), and others as described in ResearchDisclosure I. Also useful as vehicles or vehicle extenders arehydrophilic water-permeable colloids. These include synthetic polymericpeptizers, carriers, and/or binders such as poly(vinyl alcohol),poly(vinyl lactams), acrylamide polymers, polyvinyl acetals, polymers ofalkyl and sulfoalkyl acrylates and methacrylates, hydrolyzed polyvinylacetates, polyamides, polyvinyl pyridine, methacrylamide copolymers, andthe like, as described in Research Disclosure I. The vehicle can bepresent in the emulsion in any amount useful in photographic emulsions.The emulsion can also include any of the addenda known to be useful inphotographic emulsions. These include chemical sensitizers, such asactive gelatin, sulfur, selenium, tellurium, gold, platinum, palladium,iridium, osmium, rhenium, phosphorous, or combinations thereof. Chemicalsensitization is generally carried out at pAg levels of from 5 to 10, pHlevels of from 5 to 8, and temperatures of from 30 to 80° C., asdescribed in Research Disclosure I, Section IV (pages 510-511) and thereferences cited therein.

The silver halide may be sensitized by sensitizing dyes by any methodknown in the art, such as described in Research Disclosure I. The dyemay be added to an emulsion of the silver halide grains and ahydrophilic colloid at any time prior to (e.g., during or after chemicalsensitization) or simultaneous with the coating of the emulsion on aphotographic element. The dyes may, for example, be added as a solutionin water or an alcohol. The dye/silver halide emulsion may be mixed witha dispersion of color image-forming coupler immediately before coatingor in advance of coating (for example, 2 hours).

Photographic elements of the present invention are preferably imagewiseexposed using any of the known techniques, including those described inResearch Disclosure I, section XVI. This typically involves exposure tolight in the visible region of the spectrum, and typically such exposureis of a live image through a lens, although exposure can also beexposure to a stored image (such as a computer stored image) by means oflight emitting devices (such as light emitting diodes, CRT and thelike).

Photographic elements comprising the composition of the invention can beprocessed in any of a number of well-known photographic processesutilizing any of a number of well-known processing compositions,described, for example, in Research Disclosure I, or in T. H. James,editor, The Theory of the Photographic Process, 4th Edition, Macmillan,New York, 1977. In the case of processing a negative working element,the element is treated with a color developer (that is one which willform the colored image dyes with the color couplers), and then with aoxidizer and a solvent to remove silver and silver halide. In the caseof processing a reversal color element, the element is first treatedwith a black and white developer (that is, a developer which does notform colored dyes with the coupler compounds) followed by a treatment tofog silver halide (usually chemical fogging or light fogging), followedby treatment with a color developer. Preferred color developing agentsare p-phenylenediamines. Especially preferred are:

4-amino N,N-diethylaniline hydrochloride,

4-amino-3-methyl-N,N-diethylaniline hydrochloride,

4-amino-3-methyl-N-ethyl-N-(b-(methanesulfonamido) ethylanilinesesquisulfate hydrate,

4-amino-3-methyl-N-ethyl-N-(b-hydroxyethyl)aniline sulfate,

4-amino-3-b-(methanesulfonamido)ethyl-N,N-diethylaniline hydrochlorideand

4-amino-N-ethyl-N-(2-methoxyethyl)-m-toluidine di-p-toluene sulfonicacid.

Development is followed by bleach-fixing, to remove silver or silverhalide, washing and drying.

Synthesis of Dye 1-1A

6-chloro-benzothiophene dioxide (10 g, 46.3 mmol)anddiethoxymethylacetate (7.5 g, 46.3 mmol)were suspended in 150 mlacetonitrile at 25C. Triethylamine (14 g, 139 mmol) was added over 5 minproducing a golden yellow solution which was stirred 60 min. The dyesolution was poured into excess diethyl ether and the resulting solidwas collected by filtration. Isolated 10.7 g (87%) of the dye as ayellow solid. All analytical data were consistent with the structure.

Synthesis of Dye 2-1A

6-chloro-benzothiophene dioxide (10 g, 46.3 mmol)and trimethoxypropene(6.1 g, 46.3 mmol) were suspended in 200 ml ethanol at 25C.Triethylamine (14 g, 139 mmol) was added over 5 min. The mixture washeated to reflux and held for 30 min. A red solid precipitated from thehot reaction mixture. The mixture was then allowed to cool to 25° C.,and the precipitated dye was collected by filtration and washed withethanol. The collected solid was suspended in 100 mL acetonitrilel andheated to reflux while 1 mL concentrated HCl was added over 5min. Theresulting slurry was heated at reflux for 10 min, then allowed to coolto 25° C. The dye was collected by filtration, washed with acetonitrileand dried. Isolated 7.8 g (72%) of Dye 2-1A as a red/orange solid. Allanalytical data were consistent with the structure.

EXPERIMENTAL EXAMPLES Formulation A: Solid Particle Dispersion (SPD)Formulation Procedure

Step 1

Dyes were formulated as aqueous dye by ball-milling according to thefollowing procedure. Water (22.0 g) and a 10.0% solution of TritonX-200®, an alkyl aryl polyether sulfonate surfactant available from Rohmand Haas, (1.0 g) were placed in a 120 mL screw-capped bottle. A 1.0 gsample of dye was added to this solution. Zirconium oxide beads (60 mL,1.8 mm diameter) were added and the container with the cap tightlysecured was placed in a mill and the contents milled for four days. Theresulting mixture was then filtered to remove the zirconium oxide beads.The resulting aqueous dye slurries were dispersed into gelatin asdescribed in Step 2.

Step 2

Aqueous gelatin dispersions of the above dye slurries (step 1) wereprepared as follows. The vessel containing the dye slurry was removedand a known weight of dye slurry was added to a 12.5% aqueous gelatinsolution (18.0 g) at 45-80° C. This mixture was then diluted with waterto a weight of 88.87 g., yielding the final dye dispersion. In thesubsequent experimental sections gelatin containing dye dispersionsprepared in this manner will be referred to as Formulation A. The term“SPD” is used throughout simply to denote dye dispersions which havebeen formulated using well known milling techniques normally used forpreparing solid particle microcrystalline dye dispersions. This does notimply that the physical state of the dye prepared in this manner ismicrocrystalline in nature.

The dispersions described above may be prepared at a wide variety of dyeconcentrations ranging from 0.005-30% w/w. The most commonly employedconcentrations were 0.01-0.30% dye.

Formulation B: Direct Gelatin Dispersion (DGD) Formulation Procedure

Nominally 2.000 g H₂O then 0.12500 g deionized gelatin were weighed intoscrew-topped glass vials and allowed to soak at 25° C. for at least 30minutes. The swollen gelatin was then melted at 50° C. for 15 minuteswith agitation. The gelatin solution was cooled to 25° C., thenrefrigerated at 5° C. to set. Nominally 2.870 g H₂O was then added ontop of the set gelatin followed by 0.00500 g of powdered dye. The dyepowder was thoroughly wetted and dispersed in the water layer byagitation and then allowed to stand at 25° C. for 17 hours. The sampleswere then heated to 60-80° C. in a water bath for 1-2 hours and mixedwith intermittent agitation. The samples were subsequently cooled to39.0° C. over a period of approximately 1 hour and maintained at thistemperature until measurement. In the subsequent experimental sectionsdispersions prepared in this manner will be referred to as Formulation B(direct gel dispersions or DGD's).

The above formulation corresponds to a dye concentration 0.10% w/w, butthe dispersions may be prepared at a wide variety of dye concentrationsranging from 0.005-30% w/w. The most commonly employed dyeconcentrations were 0.010.30% w/w. In some instances, regularlime-processed photographic gelatin (nondecalcified) was used inpreference to deionized (decalcified) gelatin.

Example 1 Polarized-Light Optical Microscopy Test for Formation of DyeLyotropic Liquid Crystalline Phases (Liquid Crystal Phase Test)

Direct aqueous gelatin dispersions (DGD's) of known composition wereprepared as described for FormulationB for the inventive dyes and thecomparitive dyes and allowed to cool to room temperature to set. Smallaliquots of the gelled dye dispersions were then removed from the glassvials and sandwiched between a pre-cleaned glass micro slide (Gold SealProducts, USA) and a micro cover glass (VWR Scientific, USA ) to form athin film. Each slide was then viewed in polarized-light at amagnification of 16× objective using a Zeiss Universal M microscopefitted with polarizing elements.

Liquid-crystalline DGD's were readily identified by their birefringent(bright) characteristic type-textures and interference colours whenviewed in polarized light. Isotropic DGD's (solution dye, non-liquidcrystalline) were readily distinguishable from liquid-crystalline DGD'sby their complete lack of birefringency (i.e. black appearance) whenviewed in polarized light. Crystalline DGD's (solid dye, non-liquidcrystalline) were readily distinguishable from isotropic andliquid-crystalline DGD's due to the presence of finite-sized solid dyeparticles or crystals, or clumps of such solid particles or crystals,which were not readily deformable with moderate shear when pressure wasapplied to the cover glass. The gelled DGD's were then heated throughthe gel to sol transition (40°-50° C.) while observing the sample slidemicroscopically in polarized light. Dyes forming a lyotropic nematicmesophase typically displayed characteristic fluid, viscoelastic,birefringent textures including so-called Schlieren, Tiger-Skin,Reticulated, Homogeneous (Planar), Thread-Like, Droplet and Homeotropic(Pseudoisotropic). Dyes forming a lyotropic hexagonal mesophasetypically displayed viscous, birefringent Herringone, Ribbon or Fan-Liketextures. Dyes forming a lyotropic smectic mesophase displayed so-calledGrainy-Mosaic, Spherulitic, Frond-Like (Pseudo-Schlieren) andOily-Streak birefringent textures.The most preferred liquidcrystal-forming dyes of the invention clearly remained in aliquid-crystalline state at these elevated temperatures as evidencedfrom their characteristic birefringent type-textures and rheology. Insome instances, the dye liquid crystal phase melted reversibly to theisotropic dye solution phase (non-birefringent) on heating. In someinstances, the dye liquid crystal phase co-existed with solid dye. Bymaintaining the sample slide at an elevated temperature, the presenceand stability of the dye mesophase(s) could be monitored duringperipheral evaporation of the solvent to a more concentrated evaporated(dried-down) state. The most preferred dyes of the invention exhibitedmicroscopic liquid-crystalline textures in the wet gelled state, the wetmelt (sol) state and the evaporated (dried-down) state. These states(gelled, sol and evaporated) are denoted in Table 4, column 4 by theletters g, s and e in parenthesis. The dye and gelatin concentrationsrefer to the samples in the wet gelled and sol states, beforeevaporation. For some of the inventive dyes, aqueous dye dispersions ofknown composition (without gelatin) were prepared by mixing the powdereddye into water at 60° C. for 1 hour with agitation, then cooling to roomtemperature before microscopic examination.

Preferred dyes of the invention formed lyotropic liquid-crystallinephases in aqueous media at dye concentrations of ≦30% w/w, morepreferred dyes formed lyotropic liquid-crystalline phases atconcentrations of ≦10% w/w dye, even more preferred dyes formedlyotropic liquid-crystalline phases at concentrations of ≦5% w/w dye,and the most preferred dyes formed lyotropic liquid-crystalline phasesat concentrations of ≦0.5% w/w. Representative data are summarized inTable 4 below.

TABLE 4 Dye Conc. Dye # (% w/w) Solvent* Liquid Crystal Phase† 1-1 0.10D.G smectic (g, s, e) 1-1A 0.10 D.G. smectic (g, s, e) 1-2 0.20 D.G.smectic (e) 1-2A 0.20 D.G. smectic (g, s, e) 1-3 0.10 D.G. smectic (g,s, e) 1-4 0.10 D.G. smectic (g, s, e) 1-5 0.21 D.G. smectic (e) 2-1 0.25D.G. smectic (g, e) 2-1A 0.05 D.G. smectic (g, s, e) 2-2 0.15 D.G.smectic (e) 2-3 0.10 D.G. nematic (g, s, e) 2-4 0.06 D.G. smectic (g, e)2-6 0.15 D.G. smectic (e) 3-1 0.22 D.G. nematic (g, e) 3-2 0.10 D.G.nematic (g, s, e) A 0.15 D.G. none (g, s, e) B 0.13 D.G. none (g, s, e)C 0.16 D.G. none (g, s, e) D 0.21 D.G. none (g, s, e) E 0.10 D.G. none(g, s, e) F 0.11 D.G. none apparent

* D.G.=2.5% w/w aqueous Deionized (i.e. decalcified) Gelatin; R.G.=2.5%w/w aqueous Regular (non-decalcified) Gelatin. † The letters g, s and erefer to samples in the gelled, sol and evaporated states.

COMPARATIVE DYES Comparative Dye A

Comparative Dye B

Comparative Dye C

Comparative Dye D

Comparative Dye E

Comparative Dye F

Example 2 Absorption Wavelength (λ_(max)), Halfbandwidth (Hbw) and MolarExtinction Coefficients (λ_(max)) of Wet Dye DGD's (Spectral propertiesof Typical Smectic Liquid crystals of Dyes).

Direct gelatin dispersions (DGD's) of Dyes 1-1, 1-1A, 1-4, 2-1A, 2-3,2-4, and Comparative Dyes A-C were prepared as described for FormulationB. Aliquots of each dispersion, held at 39° C., were transferred to0.0066 cm pathlength glass cells and their absorption spectra measuredat 25° C. These wet dispersions are referred to as “wet DGD's”.Solutions of Dyes Dyes 1-1, 1-1A, 1-4, 2-1A, 2-3, 2-4, and ComparativeDyes A-C were prepared in a suitable organic solvent (methanol ormethanol with added triethylamine unless otherwise noted) and theirabsorption spectra measured at 25° C. The extinction coefficients forthe isotropic dye solutions and dye wet DGD's were calculated accordingto Beer's Law, and half bandwidths (Hbw) measured. The data aresummarized in Table 5.

TABLE 5 λ_(max) DGD λ_(max) soln. λ_(max) Wt % Dye (wet) Hbw DGD λ_(max)soln. (mol⁻¹ 1 cm⁻¹) Hbw soln. DGD (wet) in wet (mol⁻¹ 1 cm⁻¹) (wet) Dye(nm) ×10⁴ (nm) (nm) DGD ×10⁴ (nm) 1-1 447 4.7 57 489 0.08 15.9 12 1-1A447 4.8 56 489 0.10 19.3 12 1-4 450 3.9 61 486 0.10 12.2 16 2-1A 55211.8 57 611 0.05 36.3 22 2-3 548 10.7 56 614 0.10 17.0 17 2-4 542 10.454 614 0.06 14.2 12 A 442 3.5 56 439 0.10 6.8 59 B 550 10.8 56 537 0.1310.1 74 C 643 14.0 66 639 0.10 10.7 141 

The above results demonstrate that the direct gelatin dispersionscontaining the inventive dyes, dispersed in a smectic liquid-crystallinestate, exhibit bathochromically or hypsochromically-shifted absorptionmaxima relative to their isotropic solution (i.e. monomeric) absorptionmaxima. Moreover, the inventive dyes, when formulated as wetliquid-crystalline DGD's, exhibit higher extinction coefficients andnarrower half bandwidths compared to their non liquid-crystalline,isotropic solution states in a solvent such as methanol. Moreover, aswet liquid-crystalline DGD's the inventive dyes are far superior in bothHbw and extinction coefficient to the comparative non liquid-crystallinedyes A-C.

Example 3 Spectral Properties of Evaporated Dye DGD Coatings.

Direct gelatin dispersions (DGD's) of Dyes 1-1 to 1-5, 2-1, 2-3, 2-4,2-6, 3-1, and Comparative Dyes A-D were prepared using powdered dye asdescribed for Formulation B. Aliquots of each dispersion, held at 39°C., were then smeared onto standard glass microscope slides (0.8/1.0 mmthickness) to form uniformly thin wet films which were allowed to dry atambient temperature and humidity for at least 17 hours such that theirD_(max)(evap) was less than 4.0 absorbance units. The absorption spectrafor these evaporated gelatin films were then measured at 25° C. Thesesamples are referred to in Table 6 as “evap DGD's”. Solutions for eachof the above listed dyes were prepared in a suitable organic solvent(methanol or methanol with added triethylamine unless otherwise noted)and their absorption spectra measured at 25° C. For each dye, thedifference in absorbance maxima between the coated dye and the dyedissolved in a solvent (Δλ_(max)=(λ_(max)Evap DGD−λ_(max soln))), andthe difference in halfbandwidth between the coated dye and the dyedissolved in a solvent (ΔHbw=Hbw Evap DGD−Hbw soln) were calculated. Thedata are summarized in Table 6.

TABLE 6 λ_(max) Hbw λmax^(soln.) Evap DGD soln Hbw Evap Δλ_(max) ΔHbwDye (nm) (nm) (nm) (nm) (nm) (nm) 1-1 447 488 57 15 +38 −42 1-1A 447 48756 14 +40 −42 1-2 439 476 53 13 +37 −40 1-2A 434 477 51 13 +43 −38 1-3454 483 53 14 +29 −39 1-4 450 486 61 21 +36 −40 1-5 447 476 55 19 +29−36 2-1 552 610 58 19 +58 −39 2-1A 552 610 57 21 +58 −36 2-3 548 610 5618 +62 −38 2-4 542 609 54 15 +67 −39 2-6 543 624 39 12 +81 −27 3-1 670487 58 24 −183  −34 A 442 450 56 55  +8  −1 B 550 553 56 65  +3  +9 C643 657 66 106  +14 +40 D 662 671 66 50  +9 −16

The above results demonstrate that the direct gelatin dispersionscontaining the inventive dyes, dispersed in a smectic liquid-crystallinestate, exhibit bathochromically or hypsochromically-shifted absorptionmaxima relative to their isotropic solution (i.e. monomeric) absorptionmaxima. Moreover, the inventive dyes, when formulated as wetliquid-crystalline DGD's, exhibit higher extinction coefficients andnarrower half bandwidths compared to their non liquid-crystalline,isotropic solution states in a solvent such as methanol. Moreover, aswet liquid-crystalline DGD's the inventive dyes are far superior in bothHbw and extinction coefficient to the comparative non liquid-crystallinedyes A-D exhibit no comparable advantageous spectral changes relative totheir dissolved solution state.

Example 4 Spectral Properties of Wet and Evaporated Dye DGD's

Direct gelatin dispersions (DGD's) of Dyes 1-1 to 1-5, 2-1, 2-2 to 2-6,3-1, and Comparative Dyes A-C were prepared u sing powdered dye asdescribed for Formulation B. Aliquots of each dispersion, held at 39°C., were transferred to 0.0066 cm pathlength gl ass cells and theirabsorption spectra measured immediately at 25° C. These samples arereferred to in Table 7 as “wet DGD's”. Solution aliquots of eachdispersion were also smeared onto standard glass microscope slides(0.8/1.0 mm thickness) to form uniformly thin wet films which wereallowed to dry at ambient temperature and humidity for at least 17 hourssuch that their D_(max)(evap) was less than 4.0 absorbance units. Theabsorption spectra for these evaporated gelatin films were then measuredat 25° C. These samples are referred to in Table 7 as “Evap DGD”. Thedata are summarized in Table 7.

TABLE 7 λ_(max) λ_(max) Wet DGD Evap DGD Hbw Wet Hbw Evap Dye (nm) (nm)(nm) (nm) 1-1 489 488 12 15 1-1A 489 487 12 14 1-2 434 476 55 13 1-2A480 + 441 477 58 13 1-3 484 + 457 483 55 14 1-4 486 486 16 21 1-5 445476 59 19 2-1 546 + 611 610 >100  19 2-1A 611 610 22 18 2-3 614 610 1718 2-4 614 609 12 15 2-6 503 + 617 624 57 12 3-1 563 + 490 487 135  24 A448 450 52 54 B 537 553 74 65 C 636 657 135  106 

The above results clearly demonstrate that the useful spectral featuresof bathochromic absorbance maximum and narrow halfbandwidth for eachinventive dye in the liquid-crystalline state in wet aqueous gelatin,are largely retained in evaporated gelatin films or l ayers, and that insome cases the spectral features dramatically improve as excess water isremoved from the coating.

Example 5 Influence of Substituents on Spectral Properties of CoatedDyes

Direct gelatin dispersions (DGD's) of Dyes 1-1A, 1-2, 1-5, 2-1A, 2-3,2-4 and Comparative Dyes A and B were prepared using powdered dye asdescribed for Formulation B such that the wt % dye in each sample was0.06-0.30%. Aliquots of each dispersion were smeared onto standard glassmicroscope slides (0.8/1.0 mm thickness) to form uniformly thin wetfilms which were allowed to dry at ambient temperature and humidity forat least 17 hours such that their D_(max)(evap) was less than 4.0absorbance units. These samples are referred to as “evap DGD's”. Foreach dye, the absorbance maxima for the monomer band (λ-M_(max)), andfor the bathochromic band corresponding to the liquid crystalline phase(λ-lc_(max)) were measured for the “Evap. DGD's”, and the opticaldensities (O.D.) at the λ_(max) of the monomer band (O.D-M) and for thebathochromic band corresponding to the liquid crystal phase (O.D.-lc)were measured for the “Evap.

DGD's”, then the ratios ((O.D-lc)/(O.D-M)) were calculated. The resultsare shown in Table 8.

TABLE 8 λ-M_(max) (nm) λ- lc_(max) Evap DGD Evap DGD Evap DGD Dye (nm)(nm) (O.D. - lc/O.D. - M) 1-1A 450 488 4.6 B22550-T 1-1 452 489 4.5 1-2440 478 40 1-5 448 479 3.3 2-1A 553 610 6.0 B22551-H 2-3 560 610 4.1 2-4557 610 7.3 A 452 none 0 B 554 none 0

The above data clearly show that the presence or absence of nonionicsubstituents within a given dye class dramatically influence thepropensity of a dye to form a liquid crystalline phase. The data showsthat the inventive dyes are preferentially substituted as compared withthe comparative dyes to favor stable liquid crystal formation, and thatthe most preferred dyes have excellent ratios between the liquid crystaland monomer bands in the coatings.

Example 6 Spectral Properties of Dried Gelatin Layers Containing DyesFormulated Using Formulation A (SPD milling) and Formulation B (DGD)Procedures.

Direct gelatin dispersions of the Inventive Dyes 1-1, 1-1A and 2-1 wereprepared as described for Formulation B at concentrations equivalent todye laydowns of 0.064 g/m². Solution aliquots of each dispersion weresmeared onto glass microscope slides (0.8/1.0 mm thickness) to formuniformly thin wet films which were then allowed to dry at ambienttemperature and humidity for at least 17 hours. The absorption spectrafor these dried films were then measured at 25° C. These samples arereferred to in Table 9 as “Evap. DGD's”. The inventive dyes 1-1, 1-1Aand 2-1 were also dispersed in aqueous gelatin using the Formulation Aprocedure. These dispersions were coated on a polyester supportaccording to the following procedure. A spreading agent (Olin 10G, anisononylphenoxy glycidol surfactant available from Olin Corp.) and ahardener (bis(vinylsulfonylmethyl)ether) were added to the dye-gelatinmelt prepared as described above. A melt from this mixture was thencoated on a poly(ethylene terephthalate) support to achieve a dyecoverage of 0.043 to 0.129 g/m², a gelatin coverage of 1.61 g/m², and ahardener level of 0.016 g/m². These samples are referred to in Table 23as “Evap SPD's”. The absorption spectrum of the evaporated coating wasmeasured at 25° C. The data are summarized in Table 9.

TABLE 9 λ_(max) Hbw λ_(MAX) Hbw Evap DGD Evap DGD Evap SPD Evap SPD Dye(nm) (nm) (nm) (nm) 1-1 488 15 488 20 1-1A 487 14 488 22 2-1 610 19 61022

The data show no significant differences in λ_(max) or Hbw for the driedgelatin films containing the inventive liquid crystal-forming dyesformulated according to Formulation A (SPD)or Formulation B (DGD)procedures. Thus the advantageous spectral properties of the inventivedyes can be obtained using the simpler procedure (Formulation B) withoutthe need to resort to the more complex milling procedure (Formulation A)commonly used for solid particle dyes.

Example 7 Spectral Shape of Evaporated Dye DGD's

Direct gelatin dispersions (DGD's) of Dyes 1-1 to 1-5, 2-1 to 2-4, 3-1were prepared as described for Formulation B. Aliquots of eachdispersion were also smeared onto standard glass microscope slides(0.8/1.0 mm thickness) to form uniformly thin wet films which wereallowed to dry at ambient temperature and humidity for at least 17 hourssuch that their D_(max)(evap) was less than 2.5 absorbance units. Theabsorbance spectrum for each coated DGD was measured. Comparative solidparticle dyes D, E and F were prepared as described for Formulation A.Melts for each comparative dye were then coated on a poly(ethyleneterephthalate) support to achieve a dye coverage of 0.043 to 0.129 g/m²,a gelatin coverage of 1.61 g/m², and a hardener level of 0.016 g/m². Theabsorption maxima and half bandwidths (Hbw) of the dried coatings weremeasured at 25° C. The ratio of each dye's optical density atλ_(max)(D_(max)) to optical density (O.D.) at λ_(max)+20 nm wascalculated. The ratio of each dye's optical density at λ_(max)(D_(max))to optical density (O.D.) at λ_(max)−20 nm was also calculated. Theseratios are a measure of spectral band sharpness. Dyes with higher ratiospossess sharper cutting spectral absorption envelopes which aredesirable for light filtration/absorption applications. The data aresummarized in Table 10.

TABLE 10 λ_(max) HBW D_(max)/O.D. at D_(max)/O.D. at Dye (nm) (nm)λ_(max) + 20 nm λ_(max) − 20 nm 1-1A 487 14 >20 3.36 1-2 476 13 >20 2.31-2A 477 13 >20 3.0 1-3 483 14 >20 2.1 1-4 486 21 >20 2.3 1-5 476 19 >202.5 2-1 610 19 >20 3.5 2-1A 610 21 >20 1.8 2-3 610 18 >20 3.2 2-4 60915 >20 7.2 2-6 624 12 >20 2.3 3-1 487 24 2.5 4.4 D 676 102  1.8 1.34 E538 130  1.1 1.04 F 432 100  1.1 1.12

The data clearly demonstrate that the inventive liquid crystal-formingdyes when coated in aqueous gelatin coatings possess absorption spectrawith significantly narrower absorbance envelopes and exhibit sharperhypsochromic and bathochromic edges relative to the comparative solidparticle dyes. It should also be noted that for the inventive dyes withratios marked as “>20”, the O.D+20 nm value is sufficiently low that ithas no measurable density relative to noise. It should also be notedthat when the comparative dyes were formulated using Formulation B, thequality of the resulting coatings was very poor due to the insolubilityof the dyes in the melts. The comparative dyes were therefore milled(Formulation A) prior to coating, as is the usual procedure for solidparticle dyes. Therefore, the dyes of this invention not only possessspectral properties far superior to the comparative examples, but theirsuperior properties may be obtained without requiring the more complexFormulation A procedure by instead using the simple Formulation Bprocedure.

This example demonstrates a fundamental advantage of the inventiveliquid crystal-forming dyes over solid particle dyes. This example alsodemonstrates that the inventive liquid crystalline dyes provide sharp,narrowly absorbing spectra in coatings that are virtually unachievableusing traditional solid particle dyes.

Example 8 Covering Power of Liquid Crystalline Dyes Versus SolidParticle (microcrystalline) Analogs

Melts of Dyes 1-1, 2-1 were prepared as described for Formulation B.Melts for Comparative Dyes D, E and F were prepared as described asdescribed for Formulation A. (Formulation A was used for themicrocrystalline comparative dyes for the same reasons cited in theprevious example). Melts for each dye were then coated on apoly(ethylene terephthalate) support to achieve a dye coverage of 0.043to 0.129 g/m², a gelatin coverage of 1.61 g/m², and a hardener level of0.016 g/m². The absorption maxima and half bandwidths (Hbw) of the driedcoatings were measured at 25° C. The covering power for each of thecoated dyes was calculated by dividing the optical density (O.D.) atλ_(max) by the dye laydown in mg/ft2. The data are summarized in Table11.

TABLE 11 λ_(max) coating Dye (nm) Covering power of coated dye 1-1 4880.23 2-1 610 0.48 D 670 0.11 E 538 0.15 F 432 0.09

It is clear from the above data that coated inventive dyes possess farsuperior covering power relative to those of the comparative solidparticle dyes. It is also evident from this data that the inventiveliquid crystalline dyes allow for much smaller quantities of coatedmaterials to be used to achieve a required optical density level atD_(max) versus those of the comparative dyes. This example demonstratesanother fundamental advantage of the inventive liquid crystal-formingdyes over solid particle dyes. This example also demonstrates that theinventive liquid crystalline dyes provide sharp, narrowly absorbingspectra in coatings that are virtually unachievable by traditional solidparticle dyes.

Example 9 Dye Wandering Properties

Direct gelatin dispersion melts (Wet DGD's) were prepared for Dyes 1-1,1-2 and Comparative Dyes A and B as described for Formulation B (wt %dye 0.06-0.1). Aqueous gelatin melts containing no dye were prepared asa receiver layer and chill set detail formulation specs, i.e. 2.5 wt %gel). The set gelatin receiver pads were allowed to equilibrate at 25C.The wet DGD melts (held at 39C) were pipeted atop the gelatin receiverpads and allowed to sit for 24 hr. Observed color in the bottom layerrepresenting solubilized, mobile dye was recorded after 2 hours and 24hours on a scale of 0 to 5 with 0 being no color observed migrating and5 meaning that the upper and lower layers appeared identical in color(full equilibration). Observations are recorded in Table 12.

TABLE 12 Liquid crystal phase Observed Color Observed Color (microscopy)after 1 hour after 24 hours Dye (from Table 1) (0 to 5) (0 to 5) 1-1smectic 1 2 1-2 smectic 1 2 A none 2 3 B none 2 5

The above data clearly demonstrate that the inventive liquidcrystal-forming dyes remain largely immobile when coated, and do notappreciably migrate from the layer in which they are coated. Bycontrast, the comparative dyes migrate freely from the layer in whichthey are coated to adjacent layers. This example demonstrates afundamental advantage of the inventive liquid crystal-forming dyes oversoluble dyes widely used in the art.

Example 10 Process Removability of Dyes

The inventive Dyes 1-1, 1-1A, 1-2, 1-2A, and 2-1 were formulatedaccording to Formulation B. These dye dispersions were coated on apolyester support according to the following procedure. A spreadingagent (surfactant 10G) and a hardener (bis(vinylsulfonylmethyl)ether)were added to the dye-gelatin melt prepared as described above. A meltfrom this mixture was then coated on a poly(ethylene terephthalate)support to achieve a dye coverage of 0.043 to 0.161 g/m², a gelatincoverage of 1.61 g/m², and a hardener level of 0.016 g/m². Theabsorption spectrum of the dried coating was measured at 25° C.Identical elements were subjected to Kodak E-6® processing (which isdescribed in British Journal of Photography Annual, 1977, pp. 194-97)and the absorbance was measured for each. The results are shown in Table13.

TABLE 13 λ_(max)SPD_(dry) D_(max) Dye (nm) D_(max) after E-6 Processing1-1 488 >1.0 0.0 1-1A 488 >1.0 0.0 1-2 476 >1.0 0.0 1-2A 476 >1.0 0.02-1 610 >2.0 0.0

In spite of the inordinately high optical densities (D_(max)'s) for suchlow dye laydowns of the aggregated coated dyes, no residual deleteriousdye stain (optical density) could be detected after processing.

Example 11 Dye Immobility and Thermal Stability

The inventive Dyes 1-1, 1-1A, and 2-1 were formulated using theFormulation B and coated on a polyester support as outlined in Example.Each dye was coated at a laydown such that the measured D_(max) was lessthan 2.0. For each example, the absorbance spectrum for the dyed gelatincoating was measured both before and after incubation for seven days at120° C./50% relative humidity. The results are summarized in Table 14.

TABLE 14 D_(max) SPD Dye laydown λ_(max) SPD before D_(max) SPD afterDye (g/m²) (nm) incubation incubation 1-1 0.043 488 0.9 0.9 1-1A 0.043488 0.6 0.6 2-1 0.129 610 1.9 1.8

It is clear from the data that the liquid crystal-forming dyes in theinventive examples show an excellent robustness toward high heat andhumidity as evidenced by the fact that little or no density loss at thebathochromic λ_(max) is observed as a result of incubation. Furthermore,the absence of any detectable optical density at the monomeric λ_(max)of the inventive dyes following incubation demonstrates that little orno mobile monomeric dye species is produced under these conditions.Consequently, the inventive dyes exhibit excellent robustness andfastness to diffusion at high temperature and humidity.

In summary, the above examples demonstrate that the inventive dyessuccessfully solve the problems inherent in the filter dyes of the priorart. Soluble dyes typically migrate in coatings unless mordanted. Solidparticle dyes typically do not migrate, but their spectral envelopes aregenerally very broad, low in covering power, and not sharpcutting.Furthermore, solid particle dyes require specialized milling proceduresfor incorporation into coated elements. Our examples demonstrate thatour inventive liquid crystal-forming dyes possess the combination ofsuperior spectral characteristics of high extinction, narrow bandwidth,and sharp-cutting edges and furthermore remain immobile and thereforeallow layer-specific dyeing without the use of mordants. Moreover, manyof the liquid crystal-forming dyes of this invention are readilydecolorized or removed from the photographic element upon processing,leaving little or no post-process dye stain.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

What is claimed is:
 1. A dispersion comprising a solvent havingdispersed therein in a lyotropic liquid-crystalline phase a dye ofstructural Formula I:

wherein Q¹ and Q² represent the non-metallic atoms required to form asubstituted or unsubstituted 5 or a 6-membered heterocyclic orcarbocyclic ring, L¹ to L⁷ are substituted or unsubstituted methinegroups, M⁺ is a cation, and p, q and r are independently 0 or 1; and theresulting dye of Formula I forms a liquid-crystalline phase in solvent.2. A dispersion comprising a solvent having dispersed therein in alyotropic liquid-crystalline phase a dye of structural Formula II:

wherein R¹ to R⁴ each individually represent amino, alkylamino,dialkylamino, hydroxy, alkylthio, halogen, cyano, alkylsulfone,alkylsulfone, or substituted or unsubstituted alkyl, aryl, heteroaryl,or aralkyl, and L¹ to L⁷ each independently represents a substituted orunsubstituted methine group, M⁺ is a cation and p, q and r areindependently 0 or
 1. 3. A dispersion according to claim 1, wherein thedye of Formula II is of formula III:

wherein R⁵ to R¹² each independently represents hydrogen, substituted orunsubstituted alkyl, or cycloalkyl; alkenyl, substituted orunsubstituted aryl, heteroaryl or aralkyl; alkylthio, hydroxy,hydroxyate, alkoxy, amino, alkylamino, halogen, cyano, nitro, carboxy,acyl, alkoxycarbonyl, aminocarbonyl, sulfonamido, sulfamoyl, or groupscontaining solubilizing substituents, and any adjacent pair ofsubstituents among R⁵ through R¹² may together form a fused carbocyclicor heterocyclic aromatic or aliphatic ring; L¹ through L⁷ are eachindependently a substituted or unsubstituted methine group, M⁺ is acation, and p, q and r are independently 0, or
 1. 4. A dispersion inaccordance with claim 3, wherein each of p, q, and r is
 0. 5. Adispersion according to claim 4, wherein each of R⁵-R¹² independentlyrepresents hydrogen, halogen, alkyl, alkoxy, acyl, hydroxy, aryl orcarboxylate.
 6. A dispersion according to claim 5, wherein each ofR⁵-R¹² independently represents hydrogen, hydroxy, methyl, methoxy, orphenyl.
 7. A dispersion according to claim 3, wherein each of p is 1 andeach of q and r is
 0. 8. A dispersion according toe claim 7, wherein L²is unsubstituted or substituted with alkyl.
 9. A dispersion according toclaim 8, wherein each of R⁵-R¹² represents hydrogen, halogen, alkylalkoxy, aryl, hydroxy, carboxy or acyl.
 10. A dispersion according toclaim 9, wherein each of R⁵-R¹² independently represents hydrogen,hydroxy, methyl, methoxy, or phenyl.
 11. A dispersion according to claim3, wherein each of p and q is 1 and r is
 0. 12. A dispersion accordingto claim 11, wherein L³ is unsubstituted or substituted with alkyl andR⁵-R¹² independently represents hydrogen or alkoxy.